duumviri

from The Collaborative International Dictionary of English v.0.48

Duumvir \Du*um"vir\, n.; pl. E. {Duumvirs}, L. {Duumviri}. [L.,
   fr. duo two + vir man.] (Rom. Antiq.)
   One of two Roman officers or magistrates united in the same
   public functions.
   [1913 Webster]